1. Field of the Invention
The present invention is a brain electrode securing device, and particularly to a brain electrode securing device which holds an electrode inserted into the brain in order to measure changes in electrical potential in the nerve cells in the brains of small animals such as mice and rats and to stimulate the aforementioned brain nerve cells electrically.
2. Description of the Related Art
In order to measure changes in electrical potential in the nerve cells in the brains of small animals such as mice and rats and to stimulate the aforementioned brain nerve cells electrically, it is necessary to open a hole in the skull of the small animal and to insert an electrode through the aforementioned hole as far as a prescribed location inside the brain. This electrode is secured to the skull by means of a brain electrode securing device.
A brain electrode securing device of this type as shown in FIG. 8 was provided. In this brain electrode securing device, two screw rods 2,2 were screwed into the electrode holder 1 and the lower ends of the screw rods 2,2 were arranged with the hole a opened in the skull interposed between them and the lower ends of the aforementioned screw rods 2,2 were rotatably secured, by means of dental cement 3 etc., to the hole a opened in the skull A. Furthermore, in this brain electrode securing device, the connector casing 4 is mounted on the skull A so as to surround the screw rods 2,2, this connector casing 4 is secured to the skull A by means of dental cement 3 or the like, and the connector 6 is installed in the aforementioned connector casing 4 and the upper end of the electrode wire 5 is connected to the connector 6 using the lead 7. In such a brain electrode securing device, the electrode holder 1 is lowered by rotating the screw rods 2,2, and the tip (the electrode) 5a of the electrode wire 5 is Inserted to the prescribed position inside the brain.
However, in the aforementioned brain electrode securing device, it is necessary to arrange the electrode wire 5 perpendicularly in relation to the skull A and, because of this, the operation to install the two screw rods 2,2, in which the 2 screw rods 2,2 have to be secured in relation to the surface of the skull while their position is adjusted individually in a perpendicular direction, is laborious.
Furthermore, with the brain electrode securing device, a laborious operation is required in which, after the screw rods 2,2 have been secured, the connector casing 4 has to be fixed on the skull A, the aforementioned connector casing has to be secured and then the electrode wire 5 has to be connected using the lead 7.
In addition, in the aforementioned brain electrode securing device, when the electrode 5a is being inserted into the brain, not only is it necessary to perform a laborious operation in which the electrode holder 1 is lowered by making each of the 2 screw rods rotate slightly in relation to one another, while this operation is being performed the electrode holder 1 shakes as it is lowered so that the electrode 5 which is held in the aforementioned electrode holder 1 sways from side to side and it is difficult to perform the insertion with adequate precision.
The object of the present invention is to provide a brain electrode securing device in which the operation to install the device for securing the brain electrode and the operation to insert the electrode are easy and yet the electrode can be inserted with sufficient precision.
The present invention aimed at achieving the aforementioned object is a brain electrode securing device, in which an electrode-wire-type electrode held by an electrode holder is inserted into the brain through a hole formed in the skull in order to measure changes in electrical potential at an electrode at a measuring location inside the brain, comprising:
a casing which is fixedly mounted on the skull so as to surround the aforementioned hole;
an electrode holder which is arranged so as to slide freely in relation to the aforementioned casing; and
a screw rod which is screwed approximately to the center part of the electrode holder and is supported so as to rotate freely in relation to the aforementioned casing.
Furthermore, the brain electrode securing device according to the present invention is characterized in that a connector is secured to the casing and one end of a flexible baseboard is secured to the aforementioned electrode holder, one end of the wire of the aforementioned flexible baseboard is connected to the aforementioned connector and the other end of the wire of the aforementioned flexible baseboard is connected to the upper end of the aforementioned electrode wire.
In the brain electrode securing device according to the present invention, the electrode holder and the connector are assembled integrally in the casing. Therefore, installation operation can be completed only by mounting the casing on the skull so that the tip (the electrode) of the electrode wire fits into the hole in the skull and by securing the aforementioned casing to the skull by means of dental cement or the like.
To be precise, in the brain electrode securing device according to the invention, it is possible to ensure the screw rods are perpendicular by mounting the casing in the skull without taking into account the perpendicularity of the screw rods (perpendicularity of the electrode wire), but the electrode wire and the connector can be connected in advance so that the installation operation becomes simple.
In addition, the brain electrode securing device according to the present invention is characterized in that the casing of the device is of watertight construction and the aforementioned casing can be secured to the skull in a watertight fashion.
In the brain electrode securing device according to the invention, the casing is of watertight construction so that the underwater behavior of small animals can be assessed and yet, because no special cover is required, the device is compact and the mounting operation is easy.
The casing can be secured to the skull with a publicly known watertight construction and using publicly known materials which can be secured in a watertight fashion. For example, it is possible to use the dental cement employed in the prior art to secure the brain electrode securing device. However, in this case it is preferable to coat the outer surface of the dental cement with waterproof material.
In addition, the brain electrode securing device according to the present invention is characterized in that the casing is divided into upper and lower parts, the lower part of the casing is secured to the aforementioned skull and the upper part of he casing is connected to the aforementioned lower part of the casing.
In this brain electrode securing device according to the present invention, when it is desired to temporarily interrupt the measurement process, by detaching the upper part of the casing from the lower part of the casing it is possible to remove the main part of the device from the small animal so that the burden on it is relieved during periods when measurement is not being carried out.
The lower part of the casing can be secured to the upper part of the casing using publicly known connection means which can be connected in a watertight fashion.
Furthermore, the brain electrode securing device according to the present invention comprises a cover which is coupled to the upper portion of the aforementioned lower part of the casing and covers the opening in the upper portion of the aforementioned lower part of the casing.
In the brain electrode securing device, when the upper part of the casing is removed from the lower part of the casing the cover seals off the opening in the lower part of the casing and dirt and the like is prevented from entering the brain.